Hydrocarbon Recovery of Cannabis Compounds
🔍 CED Perspective Lens: Hydrocarbon Recovery of Cannabis Compounds
Dr. Benjamin Caplan, MD
Hydrocarbon recovery is a four step process: a source culture is grown, its compounds are pulled out with a biocompatible solvent, the extract is separated from what is not wanted, and the result is finished into a product. The diagram on this page uses the microalga Botryococcus braunii as its model, and the same sequence describes how hydrocarbon solvents such as butane are used to pull cannabinoids and terpenes out of cannabis.
The Journey of Hydrocarbon Recovery from Botryococcus braunii to Final Product
This diagram illustrates the multi-step process of hydrocarbon recovery from Botryococcus braunii colonies, a microalga known for its rich hydrocarbon content. The process begins with the cultivation and harvesting of the algal colonies. After harvesting, the next phase involves solvent extraction to isolate hydrocarbons from the algal biomass. This is followed by a separation stage to refine the extracted compounds, removing impurities and unwanted elements. Finally, the refined hydrocarbons are transformed into a finished product, ready for applications such as biofuel production or chemical synthesis.
The Four Steps in the Diagram
1. Botryococcus braunii cultures
Botryococcus braunii is a green microalga that stores a large share of its mass as long chain hydrocarbons in a matrix around its cells. Because the hydrocarbons sit outside the cell wall, a gentle solvent can recover them without destroying the culture, which is why this organism is the textbook model for hydrocarbon recovery. Seawater grown cultures of B. braunii have been studied specifically for efficient hydrocarbon extraction (Furuhashi 2013).
2. Extraction with a biocompatible solvent
The word biocompatible matters. A solvent that dissolves the target hydrocarbons but leaves living cells intact lets a processor “milk” the same culture repeatedly instead of harvesting and discarding it. The solvent contacts the biomass, the hydrocarbons partition into the solvent, and the solvent phase is drawn off.
3. Separation
The solvent now carries the target compounds plus whatever else dissolved along with them: pigments, lipids, water, and cell debris. Separation removes those passengers and recovers the solvent for reuse. In practice this stage combines settling or filtration with evaporation of the solvent, and it decides how clean the final material will be.
4. Final product
What remains after separation is the concentrated hydrocarbon fraction, ready for its end use. In the algal case that is a feedstock for fuels or chemistry. In the cannabis case, described next, it is a cannabinoid and terpene concentrate.
How This Maps onto Cannabis Extraction
In cannabis processing, “hydrocarbon extraction” means using light hydrocarbons, most often butane or propane, as the solvent. Cannabinoids and terpenes dissolve readily in these solvents at low temperature, so the extract keeps much of the aroma profile of the flower. The sequence is the same one the diagram shows: plant material in, solvent contact, separation of the solvent from the dissolved compounds, and a finished concentrate. A narrative review of medicinal cannabis processing describes hydrocarbon extraction alongside ethanol, carbon dioxide, and solventless methods, and notes that the solvent must be removed thoroughly before the product is used (Lazarjani 2021).
The main trade off is safety. Butane and propane are flammable, and amateur production has caused burns and explosions; closed loop equipment, ventilation, and laboratory testing for residual solvent are what make commercial hydrocarbon extraction acceptable (Al-Zouabi 2018). Patients reading a certificate of analysis should look for a residual solvent result on any hydrocarbon extracted product.
What This Does and Does Not Show
The diagram is a schematic of the process sequence. It does not show temperatures, pressures, solvent volumes, or yields, and it does not describe any specific commercial method. It is meant to make the logic of solvent recovery visible so that the steps in a cannabis extraction lab are easier to follow.
References
- Furuhashi K, Saga K, Okada S, Imou K. Seawater-cultured Botryococcus braunii for efficient hydrocarbon extraction. PLoS One. 2013;8(6):e66483.
- Lazarjani MP, Young O, Kebede L, Seyfoddin A. Processing and extraction methods of medicinal cannabis: a narrative review. Journal of Cannabis Research. 2021;3(1):32.
- Al-Zouabi I, Stogner JM, Miller BL, Lane ES. Butane hash oil and dabbing: insights into use, amateur production techniques, and potential harm mitigation. Substance Abuse and Rehabilitation. 2018;9:91-101.
This page is a reconstruction of the original CaplanCannabis.com diagram page. The book that grew out of that series, The Doctor-Approved Cannabis Handbook, is available here.
Frequently Asked Questions
What is hydrocarbon extraction of cannabis?
It is the use of light hydrocarbons, most often butane or propane, as a solvent to dissolve cannabinoids and terpenes out of cannabis plant material. The solvent is then separated from the dissolved compounds and removed, leaving a concentrate.
Why does the diagram use an alga instead of cannabis?
Botryococcus braunii is the textbook model for hydrocarbon recovery because it stores hydrocarbons outside its cell wall, where a gentle solvent can reach them. The four steps it illustrates, culture, solvent extraction, separation, and final product, are the same steps used for cannabis.
What does “biocompatible solvent” mean?
A solvent that dissolves the target compounds but leaves living cells intact. In algal culture that lets the same culture be extracted repeatedly instead of harvested and discarded.
Is hydrocarbon extraction safe?
Butane and propane are flammable, and amateur production has caused burns and explosions. Commercial processors use closed loop equipment, ventilation, and laboratory testing for residual solvent. Patients can check a product’s certificate of analysis for a residual solvent result.
What happens in the separation step?
The solvent carries the target compounds plus pigments, lipids, water, and cell debris. Separation removes those passengers and recovers the solvent, usually through settling or filtration followed by evaporation.
